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Abstract:

A commercial hot water system includes a boiler, a storage tank, and a
hot water delivery line connected between the storage tank and at least
one plumbing fixture along with a cold water delivery line connection
between said plumbing fixture, a cold water source and said boiler. A
pump, interconnected between the hot and cold water delivery lines,
enables circulation of water to the fixtures. A timer and controller
provides for turning on the pump and a temperature sensor, connected to
the controller, is effective in stopping the pump to prevent heated water
from being circulated through the cold water line.

Claims:

1. A commercial hot water system comprising: a boiler; a hot water
storage tank interconnected with said boiler; a hot water delivery line
connected between the storage tank and at least one plumbing fixture; a
cold water delivery line connection between said plumbing fixture, a cold
water source and said boiler; a pump connected between said boiler and
the storage tank for circulation of water from storage tank to said
fixture and return to the storage tank; a controller for causing the pump
means to circulate the water back to the hot water source when a plumbing
fixture hot water valve is turned on; a temperature sensor, connected to
said controller, for causing said controller to stop the pump in order to
prevent heated water from being circulated; and a timer, connected to
said controller, for causing the controller to turn on the pump at a
preset time.

2. The hot water system according to claim 1 wherein said temperature
sensor is configured for detecting a temperature increase and in response
thereto causing the controller to stop the pump.

3. The hot water system according to claim 1 further comprising a flow
detector, disposed in said hot water delivery line and connected to said
controller, for causing the controller to turn on the pump.

4. The hot water system according to claim I wherein said temperature
sensor is disposed in a water line connecting the hot water delivery line
and the pump.

5. The hot water system according to claim 1 wherein said temperature
sensor is configured for detecting a selected water temperature and in
response thereto causing the controller to stop the pump.

Description:

[0001] The present invention is generally directed to plumbing systems and
more particularly directed to commercial plumbing systems with energy
saving recirculation of water.

[0002] In large buildings, such as, for example, apartment buildings,
hotels, motels, and other commercial buildings, the boiler, or hot water
supply, is disposed remotely to the point of use of hot water.
Accordingly, if the water in the piping system has cooled, a user may
have to run the water for an extended period of time in order to get hot
water to a fixture.

[0003] In this case, water is wasted because the cold hot water in the
pipes is typically discharged into a drain during a period of time
waiting for the arrival of hot water. Energy is also wasted because the
discharged water was heated previously by the boiler.

[0004] This problem of both water waste and inconvenience has been solved
by providing hot water recirculation systems which are installed in
commercial buildings. Continuous circulation of hot water around the loop
is quickly available at various points of use throughout the building.
Most often, an electrically driven pump is installed at an end of a
return line which draws hot water from the supply side of the boiler and
returns it to the cold water inlet of the hot water supply.

[0005] This type of system enables quick access to hot water and, in fact,
saves water; however, it is wasteful from an energy conservation point of
view.

[0006] Even when insulated recirculation pipes have a high heat loss.
Accordingly, the heat loss from a continuously operating recirculation
system can be quite high.

[0007] In order to conserve energy, systems may be configured to turn off
the recirculation pump at specific times. This is effected through a time
clock which operates recirculation pump during the day and turns the pipe
off at night.

[0008] While this system will reduce the heat loss at night, it has a
severe drawback because recirculation is actually needed most during the
evening. That is, during the day in an apartment building or hotel/motel,
people will often use hot water at a number of fixtures throughout the
building. This water draw keeps water in the distribution system thereby
providing hot water quickly.

[0009] However, at night, very little hot water use occurs. When a person
uses hot water at night, without operation of the recirculation pump a
long time may be necessary for hot water to arrive at a remote fixture.

[0010] Accordingly, the system is desirable which enables the continuous,
or sporadic, use of recirculation to maximize efficiency of this system.
The present invention solves that problem.

SUMMARY OF THE INVENTION

[0011] A hot water delivery system in accordance with the present
invention generally includes a boiler having a storage tank
interconnected therewith and hot water delivery lines connected between
the storage tank and at least one plumbing fixture. A cold water delivery
line is provided and connected between the plumbing fixture and a cold
water source and the boiler for delivering cold water thereto.

[0012] A pump is provided which is interconnected between the boiler and
the storage tank, for circulation of the water from the storage tank to
the fixture and return to the storage tank. A controller causes the pump
to circulate water.

[0013] A temperature sensor, connected to the control system, is provided
for causing the controller to stop the pump to prevent heated water from
being circulated and a timer connected to the controller is provided for
causing the controller to turn on the pump. Alternatively, a flow
detector may be installed in the hot water delivery line and connected to
the controller for automatically causing the controller to turn on the
pump.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The advantages and features of the present invention will appear
from the following description when considered in conjunction with the
accompanying drawing, in which:

[0015] FIG. 1 is a flow diagram of a plumbing system 10 in accordance with
the present invention for a commercial establishment, such as an
apartment building, generally showing a boiler and conduits, in
communication with at least one plumbing fixture, along with a pump, flow
switch, controller, and timer.

DETAILED DESCRIPTION OF THE DRAWINGS

[0016] Referring to FIG. 1, there is shown a hot water recovery system 10
for a building 14 which generally includes a boiler 18, connected to a
storage tank 22, and supplied by a feed line 24. A hot water delivery
line 28 connecting the tank 22 with a plurality of plumbing fixtures 32
that are dispersed throughout the building 14. Also provided is a cold
water delivery line 36 interconnecting the fixtures 32 with a cold water
line 36 which is also interconnected with the boiler 18.

[0017] A pump 46 is connected between the boiler 18 and storage tank 22
for circulation of water to and from the fixture 32 in order to provide
"instant" hot water at the fixtures and a controller 50 provides for
switching electrical current from an outlet 52 to the pump 46 in order to
cause the pump 46 to circulate water from the storage tank 22 to the
fixture 32.

[0018] A temperature sensor, or flow detector, 54 may be disposed in a
line 56 interconnecting the pump 46 with the storage tank 22 and causes
the controller 50 to stop the pump 46 to prevent heated water from being
circulated. The temperature sensor 54 may be a thermistor type of
detector strapped to the outside of the line 56.

[0019] The temperature sensor 54 is preferably configured for detecting a
temperature increase, or gradient, such as one or two degrees and in
response thereto, causing the control system 52 stop the pump 46. Thus,
no matter what the actual temperature of the water in the line 56 is, an
increase of one or two degrees will cause the pump 46 to stop.
Preferably, a timer 64 may be incorporated into the controller 50 for
causing the controller 50 to turn on the pump 46 at preset times;
however, the pump is stopped by the controller 50 through the temperature
sensor 34.

[0020] Although the timer 64 is shown incorporated into the controller 50
it may be disposed anywhere in the system.

[0021] Although there has been hereinabove described a specific commercial
hot water system in accordance with the present invention for the purpose
of illustrating the manner in which the invention may be used to
advantage, it should be appreciated that the invention is not limited
thereto. That is, the present invention may suitably comprise, consist
of, or consist essentially of the recited elements. Further, the
invention illustratively disclosed herein suitably may be practiced in
the absence of any element which is not specifically disclosed herein.
Accordingly, any and all modifications, variations or equivalent
arrangements which may occur to those skilled in the art, should be
considered to be within the scope of the present invention as defined in
the appended claims.